Kinetic, mutagenic, and structural homology analysis of l-serine dehydratase from Legionella pneumophila

Xiao Lan Xu, Shawei Chen, Gregory A. Grant

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12 Scopus citations


A structural database search has revealed that the same fold found in the allosteric substrate binding (ASB) domain of Mycobacterium tuberculosis D-3-phosphoglycerate dehydrogenase (PGDH) is found in l-serine dehydratase from Legionella pneumophila. The M. tuberculosis PGDH ASB domain functions in the control of catalytic activity. Bacterial l-serine dehydratases are 4Fe-4S proteins that convert l-serine to pyruvate and ammonia. Sequence homology reveals two types depending on whether their α and β domains are on the same (Type 2) or separate (Type 1) polypeptides. The α domains contain the catalytic iron-sulfur center while the β domains do not yet have a described function, but the structural homology with PGDH suggests a regulatory role. Type 1 β domains also contain additional sequence homologous to PGDH ACT domains. A continuous assay for l-serine dehydratase is used to demonstrate homotropic cooperativity, a broad pH range, and essential irreversibility. Product inhibition analysis reveals a Uni-Bi ordered mechanism with ammonia dissociating before pyruvate. l-Threonine is a poor substrate and l-cysteine and d-serine are competitive inhibitors with K i values that differ by almost 10-fold from those reported for Escherichia coli l-serine dehydratase. Mutagenesis identifies the three cysteine residues at the active site that anchor the iron-sulfur complex.

Original languageEnglish
Pages (from-to)28-36
Number of pages9
JournalArchives of Biochemistry and Biophysics
Issue number1-2
StatePublished - Nov 2011


  • Deaminase
  • Dehydratase
  • Iron-sulfur
  • l-Serine


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